Safari Update

safari 10.1.2 is the latest version that will work in yosemite. if you have an older version of safari, open the app store and click on the updates tab. from there you will find the safari update to download and install it.

You need to upgrade your OS version to get a newer version that Safari 10.

Check the computer requirements shown in each link to see if your computer is capable of running that OS version.

Catalina

How to upgrade to macOS Mojave - Apple Support

How to get macOS High Sierra